VAC: Vaccumschmelze
MAGAMP TECHNOLOGY
Magamps to control combinational circuit parts with several output voltages
By combining materials expertise and applied knowledge, VAC developed the world's first low-cost and loss-optimised Magnetic Amplifier controllers and thus made Magamp technology accessible to modern mass markets.
In switched mode power supplies, several output voltages can be derived from one input voltage. However, only one can be controlled directly. But this means that the uncontrolled outputs will change if the loads on the controlled output change.
As a result, the other outputs need to be controlled. Classic transistor controllers are too lossy for this.
The Magamp choke takes on the position of the transistor as a magnetic switch. The output controlled with Magamp is switched in a step-down topology.
We offer:
- Z-shapes magnetisation curve (square BH loop) to reduce the control currents and reduce complexity
- Amorphous and nanocrystalline core materials to reduce switching losses
The example shows a single-ended forward converter as used in PC power supply.
The Magamp choke comprises a magnetic core with a square-shaped hysteresis loop, upon which N windings have been applied. If the Magamp choke is in the saturation Bs, its impedance is low (approaching 0, switch closed). If the Magamp choke is in an induction Breg, its impedance is ω*L. As L is very big due to the high permeability µ in the flanks of the hysteresis loop, the impedance is very high (approaching infinite, switch open).
The output controlled with Magamp is switched in a step-down topology. The Magamp choke takes on the position of the transistor as a magnetic switch.
Requirements of the Magamp chokes
Last update 2008/08/07
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